ANGLES

TYPES OF ANGLES

THIRD GRADE

INTRO

Look around and you'll start to notice lots of places where two line segments cross or meet each other at a point.

Now...

In geometry, when two lines, line segments, or rays meet each other, they make an angle.

In this lesson, let's learn more about angles!

WHAT IS AN ANGLE?

The amount of turn between two lines, line segments or rays around a common point is called the angle between them.

RIGHT ANGLE

A 90° angle is called a right angle. A right angle is marked by drawing a square at the vertex.

For example

Windows and books have right angles.

ACUTE ANGLE

An angle between 0° and 90° is called an acute angle.

FOR EXAMPLE

Pizza slices and party hats have acute angles.

OBTUSE ANGLE

An angle that is greater than 90° but less than 180° is called an obtuse angle.

For example

Roofs of houses and parts of beehives have obtuse angles.

STRAIGHT ANGLE

A 180° angle is called a straight angle. When the arms of the angle lie in the opposite direction, they form a straight angle. The angles make a straight line through the vertex.